One of the problems associated with food ice, e.g., ice cream, freezing apparatus is in providing a constant, predetermined ratio of food ice mix to air held within the freezer chamber. A number of patents disclose various, somewhat complicated, apparatus for controlling the ratio of materials discharged from a food ice reservoir into a freezing chamber in an attempt to obtain a constant flow and/or ratio of materials into the freezer chamber independent of liquid level in the food ice reservoir. Examples of such patents include the following: U.S. Pat. Nos. 2,132,364; 2,740,264; 3,019,615; and 3,256,100. In the Moser U.S. Pat. No. 3,019,615, a float controlled valve operates a valve member to vary the size of a food mix port leading from the food mix reservoir to the freezer chamber in an attempt to assure constant flow of mix into the freezer chamber despite different pressures due to different liquid levels in the food mix reservoir. The Thompson U.S. Pat. No 2,132,364, Thompson Jr. Pat. No. 2,740,264 and the Burnstein et al U.S. Pat. No. 3,256,100 disclose freezer apparatus having a float valve to provide a constant liquid level in a subsidiary reservoir by controlling flow from a main reservoir.
While the above patents each address the problem of delivering to the freezer chamber a constant flow of food ice mix and a constant ratio of food ice mix to air, the apparatus is somewhat complicated and not conducive to ice cream freezer apparatus which must be frequently cleaned and sterilized, and cannot hold the desired ratio in the freezer chamber.
The following patents have addressed the problem of attempting to obtain a constant ratio of food ice mix to air by providing various valves between the food mix reservoir and the freezer chamber at the inlet to the freezer chamber supply conduit. The Brown et al U.S. Pat. No. 3,030,976 discloses that different orifice sizes are required for mixes of different viscosities. The Vasby U.S. Pat. No. 2,972,239 and the Lutz et al U.S. Pat. No. 3,183,681 each disclose valves at the inlet of the freezer chamber in an attempt to supply a constant ratio of food ice mix to air. The Vasby U.S. Pat. No. 2,972,239 discloses a rotatable, threaded valve member; the Brown et al Pat. No. 3,030,976 discloses one or more reversible plug devices; and the Lutz et al U.S. Pat. No. 3,183,681 discloses a closure member on a spring rod alignable with nozzles.
Prior art patents disclose a recognized relationship between freezer air content and the inlet level on the supply conduit extending into the freezer chamber; see for example the Phelan U.S. Pat. No. 2,947,155 and the Lutz et al U.S. Pat. No. 3,222,035. As disclosed in the Phelan U.S. Pat. No. 2,947,155, the inlet within the freezer chamber should be located at a vertical disposition to achieve a desired air content. The Lutz et al U.S. Pat. No. 3,222,035 discloses more generally the effect of trapped air in the freezer chamber. Neither patent, however, discloses any apparatus for adjusting the level of the inlet tube within the freezer chamber for varying the air content held therein. The Moser U.S. Pat. No. 3,019,615 does not recognize the desirability of varying air content held within the freezer chamber by adjustment of supply tube height within the freezer chamber but appears to disclose an O-ring and sleeve arrangement which may be capable of vertical adjustment.